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Details On DTCs

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DTC P0126-00: (PCM, VIN Y) DETECTION CONDITION AND POSSIBLE CAUSE

DESCRIPTION Thermostat stuck open
DETECTION CONDITION Determination conditions
  • If any of the following conditions is met:

    Condition A:

    • Actual engine coolant temperature does not exceed 77 °C {171 °F} even though the estimated engine coolant temperature after the engine is started exceeds 77 °C {171 °F}.

    Condition B:

    • ECT sensor detected temperature is less than 65 °C {149 °F}
Preconditions Condition A:
  • Engine coolant temperature after engine start: 77 °C {171 °F} or less(1)
  • If the following condition is implemented 3 times or more.
    • Vehicle is driven for approx. 35.9 s at a speed of 40 km/h {25 mph}, and the frequency of engine coolant heat radiation amount (1) of 276.7 W/K is higher compared to 276.7 W/K or less
  • The actual engine coolant temperature is 18.9 °C {34 °F} higher than the estimated ambient temperature calculated by the PCM based on the values input.
  • Intake air temperature: -10-45 °C {14-113 °F}*2
  • Engine coolant temperature at engine start: -10-58 °C {14-136 °F}(2)
  • Vehicle speed: 140 km/h {87 mph} or less(2)
  • Engine speed: 5, 400 rpm or less(2)
  • Idle ratio: 50% or less
  • The following DTCs are not detected:
    • MAF sensor malfunction: P0102-00: and P0103-00:
    • ECT sensor malfunction: P0117-00: and P0118-00:
      • Fuel system malfunction: P0171-00:, P0172-00:, P2096-00:, and P2097-00:

Condition B:
  • If the following condition is implemented 3 times or more.
    • Vehicle is driven for approx. 35.9 s at a speed of 40 km/h {25 mph}, and the frequency of engine coolant heat radiation amount (1) of 276.7 W/K is higher compared to 276.7 W/K or less
  • The actual engine coolant temperature is 18.9 °C {34 °F} higher than the estimated ambient temperature calculated by the PCM based on the values input.
  • Intake air temperature: above -10 °C {14 °F}(2)
  • 2 s have passed since the engine coolant temperature above 76.9 °C {170 °F} and then below 73.9 °C {165 °F}
  • Vehicle speed: 140 km/h {87 mph} or more for 30 s or more(2)
  • Engine speed: 5, 400 rpm or more for 10 s or more(2)
  • The following DTCs are not detected:
  • MAF sensor malfunction: P0102-00: and P0103-00:
  • ECT sensor malfunction: P0117-00: and P0118-00:
    • Fuel system malfunction: P0171-00:, P0172-00:, P2096-00:, and P2097-00:
Drive cycle
Self test type
  • CMDTC self test
Sensor used
  • Desired engine coolant temperature: intake air temperature (IAT sensor), engine speed (CKP sensor), charging efficiency
  • Actual engine coolant temperature: ECT sensor
FAIL-SAFE FUNCTION
  • Not applicable
VEHICLE STATUS WHEN DTCs ARE OUTPUT
  • Illuminates check engine light.
  • Heating is ineffective after engine is started
POSSIBLE CAUSE
  • ECT sensor malfunction
  • Poor assembly of ECT sensor
  • Poor assembly of engine coolant hose (engine coolant passage malfunction)
  • Poor engine coolant, leakage, or freezing
  • Use of unspecified engine coolant
  • Foreign matter caught in thermostat (foreign matter penetration in engine coolant)
  • Thermostat malfunction
  • PCM malfunction
(1) The engine coolant heat radiation amount is the value calculated by the PCM.

(2) Standard can be verified by displaying PIDs using M-MDS
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